Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

Kenneth Kalscheur


The objective of this study was to investigate the effect of substituting soybean meal products with yeast-derived microbial protein [(YMP) DEMP; Alltech Inc., Nicholasville, KY] in diets containing two forage concentrations. Sixteen Holstein cows (4 primiparous and 12 multiparous) were randomly assigned to a replicated 4 × 4 Latin square in a 2 × 2 factorial arrangement of treatments. Diets contained low (LF; 45% of diet DM) or high forage (HF; 65% of diet DM) and YMP at 0 (NYMP) or 2.25% (WYMP) of the diet. The forage mix consisted of 67% corn silage and 33% alfalfa hay (DM basis). There were no interactions of forage and YMP for any of the production parameters. Cows fed LF consumed more DMI (26.9 vs. 25.2 kg for LF and HF, respectively; P=0.004) and produced more milk (40.1 vs. 37.83 kg; P=0.005) than cows fed HF regardless of the addition of YMP. Milk fat percentage was lower in cows fed LF compared to HF (3.76 vs. 3.94; P=0.04), whereas fat yield tended to be lower (1.52 vs. 1.45 for NYMP and WYMP respectively; P=0.07 in cows fed NYMP . Although milk protein percentage did not differ between forage concentrations with or without the addition of YMP, protein yield and total solids were greater in cows fed LF. Cows fed LF produced more energy-corrected milk (ECM) than those fed HF (41.9 vs. 40.2; P

Library of Congress Subject Headings

Dairy cattle -- Feeding and feeds
Microbial proteins
Proteins in animal nutrition


Includes bibliographical references (pages 68-78)



Number of Pages



South Dakota State University


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Included in

Dairy Science Commons